Fixes obo error in javascript int checking.

runtime/vm/object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 11389 matching lines @@
     if (FLAG_throw_on_javascript_int_overflow) {
       ThrowJavascriptIntegerOverflow(big);
     }
     return big.raw();
   }
   return Integer::New(value, space);
 }
 
 
 // This is called from LiteralToken::New() in the parser, so we can't
-// raise an exception for 54-bit overflow here. Instead we do it in
+// raise an exception for javascript overflow here. Instead we do it in
 // Parser::CurrentIntegerLiteral(), which is the point in the parser where
 // integer literals escape, so we can call Parser::ErrorMsg().
 RawInteger* Integer::NewCanonical(const String& str) {
   // We are not supposed to have integers represented as two byte strings.
   ASSERT(str.IsOneByteString());
   int64_t value;
   if (!OS::StringToInt64(str.ToCString(), &value)) {
     const Bigint& big = Bigint::Handle(Bigint::NewCanonical(str));
     ASSERT(!BigintOperations::FitsIntoSmi(big));
     ASSERT(!BigintOperations::FitsIntoInt64(big));
     return big.raw();
   }
   if ((value <= Smi::kMaxValue) && (value >= Smi::kMinValue)) {
     return Smi::New(value);
   }
   return Mint::NewCanonical(value);
 }
 
 
-// dart2js represents integers as double precision floats. It does this using
-// a sign bit and 53 fraction bits. This gives us the range
-// -2^54 - 1 ... 2^54 - 1, i.e. the same as a 54-bit signed integer
-// without the most negative number. Thus, here we check if the value is
-// a 54-bit signed integer and not -2^54
-static bool Is54BitNoMinInt(int64_t value) {
-  return (Utils::IsInt(54, value)) && (value != (-0x1FFFFFFFFFFFFFLL - 1));
+// dart2js represents integers as double precision floats, which can represent
+// anything in the range -2^53 ... 2^53.
+static bool IsJavascriptInt(int64_t value) {
+  return ((-0x20000000000000LL <= value) && (value <= 0x20000000000000LL));
 }
 
 
 RawInteger* Integer::New(int64_t value, Heap::Space space) {
   if ((value <= Smi::kMaxValue) && (value >= Smi::kMinValue)) {
     return Smi::New(value);
   }
-  if (FLAG_throw_on_javascript_int_overflow && !Is54BitNoMinInt(value)) {
+  if (FLAG_throw_on_javascript_int_overflow && !IsJavascriptInt(value)) {
     const Integer &i = Integer::Handle(Mint::New(value));
     ThrowJavascriptIntegerOverflow(i);
   }
   return Mint::New(value, space);
 }
 
 
 RawInteger* Integer::NewFromUint64(uint64_t value, Heap::Space space) {
   if (value > static_cast<uint64_t>(Mint::kMaxValue)) {
     if (FLAG_throw_on_javascript_int_overflow) {
@@ skipping 20 matching lines @@
 }
 
 
 int Integer::CompareWith(const Integer& other) const {
   UNIMPLEMENTED();
   return 0;
 }
 
 
 // Returns true if the signed Integer does not fit into a
-// Javascript (54-bit) integer.
+// Javascript integer.
 bool Integer::CheckJavascriptIntegerOverflow() const {
   // Always overflow if the value doesn't fit into an int64_t.
   int64_t value = 1ULL << 63;
   if (IsSmi()) {
     value = AsInt64Value();
   } else if (IsMint()) {
     Mint& mint = Mint::Handle();
     mint ^= raw();
     value = mint.value();
   } else {
     ASSERT(IsBigint());
     Bigint& big_value = Bigint::Handle();
     big_value ^= raw();
     if (BigintOperations::FitsIntoInt64(big_value)) {
       value = BigintOperations::ToInt64(big_value);
     }
   }
-  return !Is54BitNoMinInt(value);
+  return !IsJavascriptInt(value);
 }
 
 
 RawInteger* Integer::AsValidInteger() const {
   if (FLAG_throw_on_javascript_int_overflow &&
       CheckJavascriptIntegerOverflow()) {
     ThrowJavascriptIntegerOverflow(*this);
   }
   if (IsSmi()) return raw();
   if (IsMint()) {
@@ skipping 3032 matching lines @@
 }
 
 
 void MirrorReference::PrintToJSONStream(JSONStream* stream, bool ref) const {
   stream->OpenObject();
   stream->CloseObject();
 }
 
 
 }  // namespace dart